Nicholas John Wheeler, University of Birmingham and Matias Spektor, Fundação Getúlio Vargas. Latin America's two biggest players spent much of the 1980s in a low-grade arms race – and they both had nuclear aspirations. How did they manage to diffuse the tension?

Written by Joshua Baker and Professor Nicholas J. Wheeler. Announcing the nuclear deal agreed this week between the Islamic Republic of Iran and the so-called E3+3 (the EU3 of France, Germany and the United Kingdom plus the United States, Russia, and China), US President Barack Obama declared: 'This deal is not built on trust, it is built on verification.'

Written by Professor Stefan Wolff. South Sudan's independence in 2011, which ended half a century of deadly conflict, was met with much praise. But a descent into civil war has led to dismay and suggests fresh thinking is required.